"""
输入M和N计算C(M,N)
"""
m = int(input('m = '))
n = int(input('n = '))
fm = 1
for num in range(1,m+1):
    fm *=num
fn = 1
for num in range(1,n + 1):
    fn *=num
fm_n = 1
for num in range (1,m - n + 1):
    fm_n *= num
print(fm // fn // fm_n)